The mining industry has always been beset with disasters. Such disasters may be caused by explosions or cave-ins, and have resulted in serious injury and/or death to workers. Many of these injuries to miners (and deaths) could have been prevented had adequate systems been in place for tracking the locations of miners within a mine, and had adequate communications been in place between surface personnel and miners after electrical power in the mine had been severed. In 2006, the United States Congress identified a need for improved mining safety equipment, including the ability to track personnel at all times and to provide bi-directional communications following a disaster without the need for local (in-mine) electrical power.
Systems have been proposed and developed to address these concerns, but such systems suffer from significant drawbacks. For the needed bi-directional communications, relayed 2-way radios have been employed; however, such radios typically utilize a number of fixed stations, each requiring electrical power. Further, communication ranges of such 2-way radios tend to be too short for many mining applications. Still further, radio frequency (RF) communications are poor in many mining environments. For personnel tracking, coaxial cable systems have been proposed; however, they are known to have leakage issues that inhibit their effectiveness. Radio frequency identification (RFID) systems have also been proposed; however, such systems are typically arranged in a daisy chain configuration with multiple fixed stations, each requiring local electrical power.
Thus, a need exists for, and it would be desirable to provide improved systems for, monitoring and/or tracking of personnel.